European antitrust authorities have launched investigations into at least three oil companies on suspicion of price-fixing.

Britain’s BP, Royal Dutch Shell and Norway’s Statoil confirmed that they are subjects of the inquiry announced Tuesday by the European Union’s executive arm, the European Commission.

Statoil said a raid at its headquarters in Stavanger, Norway, was carried out with the assistance of Norwegian antitrust officials. Norway is not a member of the E.U. BP and Shell offered no details but said they were cooperating with authorities.

Platts, a division of McGraw-Hill Financial that compiles prices for energy markets, said the commission also visited its London operations Tuesday.